1. Field of the Invention
The present invention relates to an adhesive and, more particularly, to a hardener particle used for an adhesive by which semiconductor chip and TCP (tape carrier package) are connected to substrates by means of a thermal compression bonding.
2. Description of Related Art
Adhesives containing an epoxy resin as a thermosetting resin have been conventionally used in connecting semiconductor chips onto a substrate or in manufacturing electric apparatuses by connecting TCP to LCD (liquid crystal display).
The reference numeral 111 in FIG. 9A shows an LCD, and the LCD 111 has a glass substrate 112 and ITO (indium tin oxide) electrodes 113 arranged on the glass substrate 112. In connecting the LCD 111 to a TCP which will be mentioned later, an adhesive is firstly applied on the surface of the side to which the ITO electrodes 113 of the LCD 111 are arranged. The reference numeral 125 in FIG. 9B shows an adhesive applied on the LCD 111.
The reference numeral 115 in FIG. 9C shows a TCP, and the TCP 115 has a base film 116 and metal wirings 117 arranged on the surface of the base film 116. The side on which the metal wirings 117 of the TCP 115 are arranged is disposed to an adhesive 125 on the LCD 111, and after being positioned, the side to which the metal wirings 117 of the TCP 115 are arranged are arranged is pushed to the adhesive 125.
When heated as pushed in such a state, the adhesive 125 softens, and the metal wirings 117 push away the softened adhesive 125, thereby attaching to the surface of the ITO electrodes 113.
A hardener such as imidazole polymerized of an epoxy resin by heating is generally added to the adhesives mentioned as above, and when heating is further continued in a state where the metal wirings 117 are attached to the ITO electrodes 113, the epoxy resin is polymerized by a catalytic reaction of the hardener to harden the adhesive 125.
The reference numeral 101 in FIG. 9D shows an electric apparatus in a state where the adhesive 125 is hardened. In the electric apparatus 101, the TCP 115 and the LCD 111 are fixed by the hardened adhesive 125 while the metal wirings 117 are attached to the ITO electrodes 113. Accordingly, the TCP 115 and the LCD 111 are connected to each other electrically and mechanically.
However, when the above adhesive is hardened, it is necessary to heat the adhesive at the temperature of as high as not lower than 180xc2x0 C. and, if the pattern of the metal wiring 117 is fine, there may be the case where deformation such as elongation or warp is resulted in the TCP 115 upon heating. Such a problem may be solved when heating temperature is lowered but time required for the heating treatment becomes longer and productivity lowers.
With regard to adhesives having excellent hardening property at low temperature, radically polymerizable resins such as acrylate and adhesives where a radical polymerization initiator have been developed in recent years but such adhesives are inferior in electric characteristics and heat resistance in a hardened state to an adhesive using an epoxy resin.
The present invention has been created for solving the above-mentioned inconveniences in the prior art, and its object is to provide an adhesive able to be hardened under the condition of lower temperature and short time and also has excellent preserving property.
The inventor of the present invention has paid an attention to a means where commonly used hardeners are not used but an epoxy resin is subjected to a cationic polymerization and carried out the investigation repeatedly and, as a result, it has been that, when a silane compound having at least one alkoxy group in a structure (a silane coupling agent) and a metal chelate (or a metal alcoholate) are added to an adhesive, silanol where the silane coupling agent is hydrolyzed and cation where the metal chelate is reacted are produced and then the epoxy resin is polymerized by the cation.
The step of hardening of the epoxy resin by an adhesive to which metal chelate and silane coupling agent are added will be illustrated by the following reaction formulae (5) to (8). 
As shown in the reaction formula (5), a silane compound having at least one alkoxy group reacts with water in the adhesive whereupon the alkoxy group is hydrolyzed to give a silanol group.
When the adhesive is heated, the silanol group reacts with metal chelate such as aluminum chelate and the silane compound is bonded to the aluminum chelate (the reaction formula (6)).
After that, as shown in the reaction formula (7), another silanol remaining in the adhesive in an equilibrium reaction is arranged to the aluminum chelate to which the silanol is bonded whereupon Bronsted acid points are produced and, as the reaction formula (8) shows, an epoxy ring located at the end of the epoxy resin is opened by the activated proton and is polymerized with an epoxy ring of another epoxy resin (cationic polymerization). As such, when a silane coupling agent and a metal chelate are added to an adhesive, a thermosetting resin such as epoxy resin is cationically polymerized. Since the reactions as shown by the reaction formulae (6) to (8) proceed at lower temperature than the temperature (180xc2x0 C.) at which the conventional adhesives are hardened, the adhesive as mentioned above hardens at lower temperature within shorter time than in the case of the conventional ones.
However, a silane coupling agent is apt to be hydrolyzed and, in addition, reactivity of the silanol with a metal chelate or a metal alcoholate is high. Therefore, when a powdery metal chelate or metal alcoholate is directly dispersed to an adhesive as hardener particles, polymerization reaction of an epoxy resin proceeds even at ambient temperature and preservation property of the adhesive becomes poor.
The present inventor has carried out further intensive investigation and, as a result, it has been found that preserving property of the adhesive becomes high when a compound having hydroxyl group such as alcohol or a silane coupling agent is contacted to the surface of the hardener particles before addition of the hardener particles to an adhesive so that the compound is made to react with the central metal of the surface of the hardener particle.
The present invention has been constituted on the basis of the above-mentioned findings. A hardener particle mainly according to the invention includes either metal chelate where at least one ligand is coordinated to central metal or a metal alcoholate where at least one alkoxy group is bonded to central metal or both, wherein silicon is bonded to the central metal located on the surface of the hardener particles via oxygen.
In a preferred embodiment, the silicon is bonded to the central metal are bonded to each other via oxygen. A substituent bonded to the silicon may be represented by the following formula (1) or formula (2) 
(the substituent X1 in the above formula is bonded to the silicon), 
(at least one substituent among the substituents X2xcx9cX4 in the above formula (2) is bonded to the silicon)
Herein, exemplified as substituent X1 are, e.g., xe2x80x94CH2CH2CH2xe2x80x94, xe2x80x94CH2CH2CH2NHCH2CH2xe2x80x94, xe2x80x94CH2CH2CH2NHC(xe2x95x90O)xe2x80x94. Exemplified substituents X2 to X4 are, e.g., phenyl group, H, xe2x80x94(CH2)nxe2x80x94 (n is integer). The substituents X2 to X4 coupling to silicon, among them, can be, e.g., xe2x80x94CH2CH2CH2NHCH2CH2xe2x80x94, xe2x80x94CH2CH2CH2NHC(xe2x95x90O)xe2x80x94.
In another aspect of the invention, a hardener particle mainly includes either metal chelate where at least one ligand is coordinated to central metal or a metal alcoholate where at least one alkoxy group is coordinated to central metal or both, and the hardener particles in which carbon is bonded to the central metal located on the surface of the hardener particles via oxygen.
In further aspect of the invention, a manufacturing method for a hardener particle, includes the steps of forming silanol in hydrolyzing a silane coupling agent represented by the following formula (3) 
(at least one of the substituents X5xcx9cX8 in the above formula (3) is an alkoxy group), and forming a siloxane represented by the following formula (4) 
(in the above formula (4), oxygen which is bonded to silicon is bonded to the central metal) upon contacting hardener particles mainly comprising either or both of a metal chelate in which at least one ligand is bonded to a central metal or a metal alcoholate in which at least one alkoxy group is bonded to a central metal to the above silanol to react the central metal located on the surface of the hardener particles with the above silanol.
According to a preferred embodiment, with the manufacturing method for the hardener particle, an epoxy resin is made to react with at least one substituent among the substituents X9xcx9cX11 bonding to silicon of the siloxane represented by the above formula (4); the substituent reacting with the epoxy resin has an amino group in its structure.
In yet another aspect of the invention, a manufacturing method for a hardener particle includes the steps of contacting hardener particles mainly including either or both of a metal chelate in which at least one ligand is coordinated to a central metal or a metal alcoholate in which at least one alkoxy group is bonded to a central metal to a compound having a hydroxyl group, and reacting the central metal located on the surface of the hardener particles with the compound having a hydroxyl group.
In a preferred embodiment, the compound having a hydroxyl group may include an alcohol; the alcohol may include tripropylene glycol.
In another aspect, an adhesive according to the invention, has a thermosetting resin, a silane coupling agent, and the hardener particle as set forth above.